An international team of scientists has used the NASA/ESA Hubble Space Telescope to study the atmosphere of the hot exoplanet WASP-39b. WASP-39b is orbiting a Sun-like star, about 700 light-years from Earth. The exoplanet is classified as a “Hot-Saturn,” reflecting both its mass being similar to the planet Saturn in our own Solar System and its proximity to its parent star. This study found that the two planets, despite having a similar mass, are profoundly different in many ways. Not only is WASP-39b not known to have a ring system, it also has a puffy atmosphere that is free of high-altitude clouds.
By dissecting starlight filtering through the planet’s atmosphere the team found clear evidence for atmospheric water vapour. In fact, WASP-39b has three times as much water as Saturn does.
— source spacetelescope.org